MAGNETIC-PROPERTIES AND THERMAL-STABILITY OF FE-B AMORPHOUS FILMS

Magnetic properties of Fe1-xBx sputtered films were investigated in the range 0.09<x<0.49. Due to the large magnetostrictions already reported for rapidly quenched ribbons, the films are very sensitive to the annealing process. Change of internal stress by annealing was measured. The stress is tensile in the as-deposited samples and it continues to increase with successive annealing on fused-quartz substrates but decreases on substrates with a larger thermal expansion coefficient. This decrease of tensile stress and a shape anisotropy of a columnar structure develop a perpendicular anisotropy to the film plane and increase Hc. However, a thermally stable composition was found, where the films maintain magnetic softness up to near the crystallization temperature, irrespective of different thermal propeties of the substrates.